Streptozotocin (STZ)-Induced Diabetes Affects Tissue Trace Element Content in Rats in a Dose-Dependent Manner

Comparative Screening of the Liver Gene Expression Profiles from Type 1 and Type 2 Diabetes Rat Models

Experimental animal models of diabetes can be useful for identifying novel targets related to disease, for understanding its physiopathology, and for evaluating emerging antidiabetic treatments. This study aimed to characterize two rat diabetes models: HFD + STZ, a high-fat diet (60% fat) combined with streptozotocin administration (STZ, 35 mg/kg BW), and a model with a single STZ dose (65 mg/kg BW) in comparison with healthy rats. HFD + STZ- induced animals demonstrated a stable hyperglycemia range (350-450 mg/dL), whereas in the STZ-induced rats, we found glucose concentration values with a greater dispersion, ranging from 270 to 510 mg/dL. Moreover, in the HFD + STZ group, the AUC value of the insulin tolerance test (ITT) was found to be remarkably augmented by 6.2-fold higher than in healthy animals (33,687.0 ± 1705.7 mg/dL/min vs. 5469.0 ± 267.6, respectively), indicating insulin resistance (IR). In contrast, a more moderate AUC value was observed in the STZ group (19,059.0 ± 3037.4 mg/dL/min) resulting in a value 2.5-fold higher than the average exhibited by the control group. After microarray experiments on liver tissue from all animals, we analyzed genes exhibiting a fold change value in gene expression <-2 or >2 (p-value <0.05). We found 27,686 differentially expressed genes (DEG), identified the top 10 DEGs and detected 849 coding genes that exhibited opposite expression patterns between both diabetes models (491 upregulated genes in the STZ model and 358 upregulated genes in HFD + STZ animals). Finally, we performed an enrichment analysis of the 849 selected genes. Whereas in the STZ model we found cellular pathways related to lipid biosynthesis and metabolism, in the HFD + STZ model we identified pathways related to immunometabolism. Some phenotypic differences observed in the models could be explained by transcriptomic results; however, further studies are needed to corroborate these findings. Our data confirm that the STZ and the HFD + STZ models are reliable experimental models for human T1D and T2D, respectively. These results also provide insight into alterations in the expression of specific liver genes and could be utilized in future studies focusing on diabetes complications associated with impaired liver function.

Nano-Stevia reduces the liver injury caused by streptozotocin (STZ)-induced diabetes in rats by targeting PEPCK/GCK genes, INSR pathway and apoptosis

Objectives

Extensive application of stevia in the treatment of type 2 diabetes mellitus (DM) has been proven by a large number of previous studies. We prepared stevia loaded in nanoniosomes (nanostevia) to improve its bioavailability, functionality, and stability and explore its protective effects and underlying mechanisms in the liver of STZ-induced diabetic rats.

Methods

Single-dose intraperitoneal injection of STZ (50 mg/kg body weight) was used to establish diabetic model. The mRNA levels of PEPCK and GCK genes and the protein level of INSR were evaluated by Real time-PCR and Western blot assays, respectively. TUNEL assay was used to detect apoptotic cell death in the liver tissue.

Results

Diabetic rats exhibited significantly reduced levels of INSR (*** P < 0.001) as well as elevated levels of PEPCK (*** P < 0.001). Both stevia and nano-stevia were capable of increasing levels of GCK and INSR and reducing levels of PEPCK (## P < 0.01 and ### P < 0.001, respectively). In addition, significantly increased number of apoptotic cell death was seen in the liver tissue of diabetic rats (*** P < 0.001) which was markedly mitigated by treatment with both Stevia and nano-Stevia (#P < 0.05 and ## P < 0.01, respectively).

Conclusion

Both stevia and nano-stevia demonstrates potent anti-apoptotic activity in the liver tissue of diabetic rats by targeting PEPCK/GCK genes and INSR pathway. These finding show that nano-stevia has more potential to reduce the liver injury caused by STZ-induced diabetes in rats and hence can be considered a valid agent and alternative therapy for attenuating complications of type 2 DM.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-023-01278-2.

Ameliorative effect of Stevia rebaudiana Bertoni on sperm parameters, in vitro fertilization, and early embryo development in a streptozotocin-induced mouse model of diabetes

Diabetes mellitus (DM) is a common metabolic disease characterized by high blood sugar levels. It is well known that men with diabetes frequently experience reproductive disorders and sexual dysfunction. In fact, sperm quality has a significant effect on fertilization success and embryo development. The current study aimed to investigate the effect of Stevia rebaudiana hydroalcoholic extract on serum testosterone levels, sperm parameters, in vitro fertilization (IVF) success, and in vitro embryonic developmental potential to reach the blastocyst stage in a streptozotocin (STZ)-induced mouse model of diabetes. In this research, 30 male mice were distributed randomly into control, diabetic (streptozotocin 150 mg/kg) and diabetic + Stevia (400 mg/kg) groups. The results revealed a decrease in body and testis weight and elevated blood fasting blood sugar (FBS) levels in the diabetic group, compared with the control. However, Stevia treatment significantly increased body and testis weight, while serum FBS levels were decreased compared with the diabetic group. In addition, Stevia significantly increased blood testosterone levels compared with the diabetic group. Moreover, sperm parameters were improved considerably by Stevia treatment compared with the diabetic group. Furthermore, Stevia administration significantly promoted IVF success rate and in vitro development of fertilized oocytes compared with the diabetic group. In summary, our data indicated that Stevia enhanced sperm parameters, IVF success, and in vitro embryonic developmental competency in diabetic mice, probably because of its antioxidant effects. Therefore, Stevia could ameliorate sperm parameters that, in turn, increase fertilization outcomes in experimental-induced diabetes.

Rodent Models of Diabetic Retinopathy as a Useful Research Tool to Study Neurovascular Cross-Talk

Diabetes is a group of metabolic diseases leading to dysfunction of various organs, including ocular complications such as diabetic retinopathy (DR). Nowadays, DR treatments involve invasive options and are applied at the sight-threatening stages of DR. It is important to investigate noninvasive or pharmacological methods enabling the disease to be controlled at the early stage or to prevent ocular complications. Animal models are useful in DR laboratory practice, and this review is dedicated to them. The first part describes the characteristics of the most commonly used genetic rodent models in DR research. The second part focuses on the main chemically induced models. The authors pay particular attention to the streptozotocin model. Moreover, this section is enriched with practical aspects and contains the current protocols used in research in the last three years. Both parts include suggestions on which aspect of DR can be tested using a given model and the disadvantages of each model. Although animal models show huge variability, they are still an important and irreplaceable research tool. Note that the choice of a research model should be thoroughly considered and dependent on the aspect of the disease to be analyzed.

ATF3/SPI1/SLC31A1 Signaling Promotes Cuproptosis Induced by Advanced Glycosylation End Products in Diabetic Myocardial Injury

Cuproptosis resulting from copper (Cu) overload has not yet been investigated in diabetic cardiomyopathy (DCM). Advanced glycosylation end products (AGEs) induced by persistent hyperglycemia play an essential role in cardiotoxicity. To clarify whether cuproptosis was involved in AGEs-induced cardiotoxicity, we analyzed the toxicity of AGEs and copper in AC16 cardiomyocytes and in STZ-induced or db/db-diabetic mouse models. The results showed that copper ionophore elesclomol induced cuproptosis in cardiomyocytes. It was only rescued by copper chelator tetrathiomolybdate rather than by other cell death inhibitors. Intriguingly, AGEs triggered cardiomyocyte death and aggravated it when incubated with CuCl₂ or elesclomol-CuCl2. Moreover, AGEs increased intracellular copper accumulation and exhibited features of cuproptosis, including loss of Fe-S cluster proteins (FDX1, LIAS, NDUFS8 and ACO2) and decreased lipoylation of DLAT and DLST. These effects were accompanied by decreased mitochondrial oxidative respiration, including downregulated mitochondrial respiratory chain complex, decreased ATP production and suppressed mitochondrial complex I and III activity. Additionally, AGEs promoted the upregulation of copper importer SLC31A1. We predicted that ATF3 and/or SPI1 might be transcriptional factors of SLC31A1 by online databases and validated that by ATF3/SPI1 overexpression. In diabetic mice, copper and AGEs increases in the blood and heart were observed and accompanied by cardiac dysfunction. The protein and mRNA profile changes in diabetic hearts were consistent with cuproptosis. Our findings showed, for the first time, that excessive AGEs and copper in diabetes upregulated ATF3/SPI1/SLC31A1 signaling, thereby disturbing copper homeostasis and promoting cuproptosis. Collectively, the novel mechanism might be an alternative potential therapeutic target for DCM.

The influence of high-fat and high-sucrose feeding regimes on organ weight, body weight, and serum concentration of bioelements in rats

BACKGROUND

Obesity is one of the most common diseases of civilization, and approximately 13 % of the world's adult population is obese. Obesity is defined as excessive accumulation of fat in the human body, which leads to adverse health effects such as metabolic syndrome, type 2 diabetes, and fatty liver disease (e.g., nonalcoholic liver disease). The development of obesity is accompanied by changes in the levels of certain bioelements such as copper and zinc. These elements may have an influence on the proper functioning of the central nervous system.

METHOD

Fifty-six male Wistar rats (initial weight 290-300 g) were divided into seven experimental groups. They were fed with different feeding patterns (constant versus intermittent-binge access) and exposed to different diets (high sucrose versus high fat) to analyze the factors that affect the organ weight gain (pancreas, spleen, liver, testes, and kidneys) and total body weight gain. Further, zinc and copper levels in the serum of the animals were determined. The relationship between organ and body weight and serum metal concentration was analyzed by cluster and principal component analyses.

RESULTS

Rats with unlimited access to high fat diet (HF) and restricted intake of high sugar diet (for 2-hours daily-HSB and every second day-IHSB) have elevated body weight in comparison to the control. However, the heaviest organ weights were recorded in the HSB rats compared to the control group (pancreas, 14 %; spleen, 9 %; kidneys, 5 %; and liver, 3 %). On the other hand, an average 20 % decrease in zinc concentration was observed in rats fed with high-fat diet compared to the control. Moreover, an 18 % decrease in copper levels was observed in rats that had periodic access to high-fat diet every 2 h daily and for 2 h every other day compared to the control.

CONCLUSION

Both the high-sucrose and high-fat diets had an influence on body and organ weights. This study demonstrates an association between the different types of diet and the parameters investigated (body and organ weights and concentration of serum bioelements).

ZIP14 is involved in iron deposition and triggers ferroptosis in diabetic nephropathy

Ferroptosis is caused by lipid peroxidation and iron accumulation and can cause cell death. Abnormally expressed iron transporters are involved in ferroptosis in a variety of diseases. ZRT/IRT-like protein 14 (ZIP14) is a transport protein that can mediate cellular uptake of iron, zinc and manganese. Herein, we have tested the hypothesis that the divalent metal transporter ZIP14 is involved in the initiation of ferroptosis in diabetic nephropathy (DN). DN was induced in eight-week old male rats by streptozotocin (STZ) before analysis of the degree of renal tubular injury. In addition, an in vitro model of DN in HK2 cells was used. We showed that ZIP14 was upregulated and Fe2+ levels increased both in vivo and in vitro. Expression of glutathione peroxidase 4 (GPX4) and the level of glutathione (GSH) were reduced, whereas that of malondialdehyde (MDA) increased. Ferrostatin-1(Fer-1) treatment reduced the expression of ZIP14 and the levels of Fe2+ and MDA, which is consistent with ferroptosis. Fer-1 improved kidney function in DN rats. This was characterized by urine levels of protein-to-creatinine ratio, α 1-microglobulin and N-acetyl-β-D-glucosaminidase. Our study demonstrates a novel role for ZIP14 in diabetic kidney injury mediated by ferroptosis, and suggests a potential new therapeutic approach for the treatment of diabetic nephropathy.

Effect of Bis(maltolato)oxovanadium(IV) on Zinc, Copper, and Manganese Homeostasis and DMT1 mRNA Expression in Streptozotocin-Induced Hyperglycemic Rats

Our aim was to examine whether vanadium (IV) corrects alterations in zinc, copper and manganese homeostasis, observed in streptozotocin-induced hyperglycemic rats, and whether such changes are related to divalent metal transporter 1 (DMT1) mRNA expression, and antioxidant and proinflammatory parameters. Four groups of Wistar rats were examined: control; hyperglycemic (H); hyperglycemic treated with 1 mg V/day (HV); and hyperglycemic treated with 3 mg V/day (HVH). Vanadium was supplied in drinking water as bis(maltolato)oxovanadium(IV) for five weeks. Zinc, copper and manganese were measured in food, excreta, serum and tissues. DMT1 mRNA expression was quantified in the liver. Hyperglycemic rats showed increased Zn and Cu absorption and content in the liver, serum, kidneys and femurs; DMT1 expression also increased (p < 0.05 in all cases). HV rats showed no changes compared to H rats other than decreased DMT1 expression (p < 0.05). In the HVH group, decreased absorption and tissular content of studied elements (p < 0.05 in all cases) and DMT1 expression compared to H (p < 0.05) were observed. Liver zinc, copper and manganese content correlated positively with glutathione peroxidase activity and negatively with catalase activity (p < 0.05 in both cases). In conclusion, treatment with 3 mg V/d reverted the alterations in zinc and copper homeostasis caused by hyperglycemia, possibly facilitated by decreased DMT1 expression.

Quercetin Beneficial Role in the Homeostatic Variation of Certain Trace Elements in Dyslipidemic Mice

Background

Quercetin's role in the homeostasis of certain trace elements in dyslipidemia induced in mice was assessed.

Methods

Forty BALB/c mice were allocated into 4 groups as follows: control; HFD, received fat diet; HFD + Q group, received HFD +500 mg/L quercetin; and blank control (Q)-normal food + 500 mg/L quercetin in drinking water.

Results

By analyzing the values of total proteins, albumins, cholesterol, triglycerides, HDL cholesterol, LDL cholesterol, and the levels of several trace elements in blood and organs, we perceived a statistically significant increase ( ∗∗ , p < 0.01) of TP, ALB, TC, TGE, and LDL-c. A nonsignificant decrease was ascertained to HDL-c value in the HFD and quercetin groups (p > 0.05). In the HFD group, all analyzed elements in the kidney and spleen increased, also Cu, Li, Mg, Mn, Pb, and of B, Ba, Cr, Cd, Cu, Fe, Li, Mn, Ni, Pb, and Zn in the heart increased, but furthermore, Ag, B, Ba, Cd, Cr, Fe, Ni, and Zn in blood, Ag and Zn in the liver, and Cd in the spleen decreased. In the HFD group who received quercetin, elements (except B) were decreased in kidney and liver, also increased Ag, Ba, Cr, Fe, Li, Ni, Zn in blood, but similarly, Ag, B, Ba, Cd, Cu, Mn, and Pb declined in the spleen and heart.

Conclusions

Results proved the quercetin beneficial role.

Kidney Adaptations Prevent Loss of Trace Elements in Wistar Rats with Early Metabolic Syndrome

Metabolic syndrome (MetS) represents a cluster of related metabolic abnormalities, including central obesity, hypertension, dyslipidemia, hyperglycemia, and insulin resistance. These metabolic derangements present significant risk factors for chronic kidney disease that carries to loss of essential micronutrients, which accelerates comorbidity apparition. The work aimed was to evaluate the trace element homeostasis regarding morphological adaptations and renal function in MetS early-onset. Fifty male Wistar rats were divided into two groups: (a) control group and (b) hypercaloric diet group that developed MetS early-onset after 3 months. Classical zoometric parameters do not show changes; however, biochemical modifications were observed such as hyperglycemia, protein glycation, insulin resistance, dyslipidemia, hyperinsulinemia, and hypoadiponectinemia. MetS early-onset group observed renal structural modifications, but no functional changes. The structural modifications observed were minimal glomerular injury, glomerular basement membrane thickening, as well as mesangial and tubular cells that showed growth and proliferation. In serum and kidney (cortex and medulla), the concentrations of Zn, Fe, Cr, Mg, Mn, Cu, Co, and Ni were no differences between the experimental groups, but excretory fractions of these were lower in the hypercaloric diet group. In conclusion, MetS early-onset coexist renal structural modification and a hyperreabsorptive activity of essential trace elements that avoid its loss; thus, the excretory fraction of oligo-elements could be used a biomarker of early renal injury caused by metabolic diseases in the clinical practice.

Streptozotocin induces brain glucose metabolic changes and alters glucose transporter expression in the Lobster cockroach; Nauphoeta cinerea (Blattodea: Blaberidae)

The development of new models to study diabetes in invertebrates is important to ensure adherence to the 3R's principle and to expedite knowledge of the complex molecular events underlying glucose toxicity. Streptozotocin (STZ)-an alkylating and highly toxic agent that has tropism to mammalian beta cells-is used as a model of type 1 diabetes in rodents, but little is known about STZ effects in insects. Here, the cockroach; Nauphoeta cinerea was used to determine the acute toxicity of 74 and 740 nmol of STZ injection per cockroach. STZ increased the glucose content, mRNA expression of glucose transporter 1 (GLUT1) and markers of oxidative stress in the head. Fat body glycogen, insect survival, acetylcholinesterase activity, triglyceride content and viable cells in head homogenate were reduced, which may indicate a disruption in glucose utilization by the head and fat body of insects after injection of 74 and 740 nmol STZ per nymph. The glutathione S-transferase (GST) activity and reduced glutathione levels (GSH) were increased, possibly via activation of nuclear factor erythroid 2 related factor as a compensatory response against the increase in reactive oxygen species. Our data present the potential for metabolic disruption in N. cinerea by glucose analogues and opens paths for the study of brain energy metabolism in insects. We further phylogenetically demonstrated conservation between N. cinerea glucose transporter 1 and the GLUT of other insects in the Neoptera infra-class.

Evaluation of biomarkers in liver following Solanum melongena green calyx administration in diabetic rats

Background

Solanum melongena green calyx (SMGC) has antioxidant properties. Diabetes mellitus (DM) increases oxidative stress and causes cellular damages in liver. This study attempts to show the protective effects of SMGC against morphometric, inflammatory, oxidative, and apoptotic changes in liver following DM induction.

Methods

For DM induction, the streptozotocin (60 mg/kg) was injected intraperitoneally. After the preparation of the SMGC extract, phytochemical content was analyzed. Sixty-four rats were categorized into 8 groups (n = 8); control, diabetic, SMGC, and diabetic + SMGC. SMGC administration was applied orally with doses of 100, 300, 500 mg/kg for 4 weeks. The assays of nitrite oxide, lipid peroxidation (LP), and Ferric Reducing Ability of Plasma (FRAP) were conducted for sample analysis. P53, Bcl2, and Bax genes expression, inflammatory cytokines, enzymes, and morphological features were measured. Apoptotic cell index, body weight, and levels of glucose and insulin were also analyzed. A one-way ANOVA test was used for statistical analysis.

Result

According to the phytochemical analysis, the SMGC is rich in Tannins and Saponins. Antioxidant values, p53 and Bax genes expression, inflammatory cytokines, enzymes, body weight, serum glucose, and morphometrical features were increased significantly (except insulin and FRAP levels and Bcl2 gene expression which were decreased) in diabetic group compared to the control group (P < 0.05). Also, evaluated parameters were reduced significantly (except insulin and FRAP levels and Bcl2 gene expression which were increased) in SMGC and diabetic + SMGC groups in comparison with the diabetic group (P < 0.05).

Conclusion

These findings revealed that the SMGC attenuates blood glucose levels in diabetic animals and also eliminates destructive effects of DM on liver through antioxidant features.